Matrix-assisted laser desorption ionization peptide mapping

JENSEN, O.N., PODTELEJNKOV, A., MATTHIAS-MANN, M., Delayed extraction improves specificity in database searches by matrix-assisted laser desorption/ionization peptide maps, Rapid Comm. Mass Spectrom., 1996,10, 1371-1378. 

Kussmann, M. et al.. Matrix-assisted laser desorption/ionization mass spectrometric peptide mapping of the neural cell adhesion protein neurolin purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis or acidic precipitation.. Mass Spec., 32, 483,1997. 

Humeny A, Kislinger T, Becker CM, Pischetsrieder M. Qualitative detennination of specific protein glycation products by matrix-assisted laser desorption/ionization mass spectrometry Peptide mapping. J Agric Food Client 2002 50(7) 2153—2160. 

Matrix-assisted laser desorption-ionization ionizes molecules with molecular masses of 100-1,000,000 Da for analysis by MS and provides high sensitivity, high throughput, and simplicity of operation. MALDI combined with enzymatic reactions and protein chemistry can provide very useful information on molecular masses, peptide maps, and primary structure.15 MALDI-TOF MS can quickly and accurately determine unfractionated mixtures at concentrations below 100 fmol per liter. The obtained data are then calibrated with internal standards, monoisotopic masses are assigned for all prominent peaks, and the peptide list thus generated is used to identify the protein by using a suitable database.16... 

Wang, Q. Jakubowski, J. A. Sweedier, J. V. Bohn, P. W., Quantitative submonolayer spatial mapping of Arg-Gly-Asp-containing peptide organo-mercaptan gradients on gold with matrix-assisted laser desorption/ionization mass spectrometry, Anal. Chem. 2004, 76, 1-8... 

Biological materials often contain proteins that must be identified. Recent advances in mass spectrometry have made peptide mapping a convenient tool for this purpose. The protein in question is selectively hydrolyzed with a peptidase such as trypsin and the mixture of peptides produced is analyzed by matrix-assisted laser desorption ionization (MALDI) as illustrated in Figure 25.10. 

Figure 9 (A) Reflector MALDI mass spectrum of an in situ digest of apo-transferrin taken from the 2D map of rat sera displayed in Figure 4, which were alkylated with do-acrylamide and ds-acrylamide and mixed in a 30/70% ratio. (B) and (C) are two short intervals taken from (A), and are associated with the two indicated peptide sequences. (Reproduced from Gehanne S, Cecconi D, Carboni L, et al. (2002) Quantitative analysis of two-dimensional gel-separated proteins using isotopically marked alkylating agents and matrix-assisted laser desorption/ionization mass spectrometry. Rapid Communications in Mass Spectrometry 16 1692-1698.)...

Mass spectrometry is a powerful qualitative and quantitative analytical tool that is used to assess the molecular mass and primary amino acid sequence of peptides and proteins. Technical advancements in mass spectrometry have resulted in the development of matrix-assisted laser desorption/ion-ization (MALDI) and electrospray ionization techniques that allow sequencing and mass determination of picomole quantities of proteins with masses greater than 100kDa (see Chapter 7). A time-of flight mass spectrometer is used to detect the small quantities of ions that are produced by MALDI. In this type of spectrometer, ions are accelerated in an electrical field and allowed to drift to a detector. The mass of the ion is calculated from the time it takes to reach the detector. To measure the masses of proteins in a mixture or to produce a peptide map of a proteolytic digest, from 0.5 to 2.0 p.L of sample is dried on the tip of tlie sample probe, which is then introduced into tire spectrometer for analysis. With this technique, proteins located on the surfaces of cells are selectively ionized and analyzed. 

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